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See detailFirst Characterization of the Volatile Organic Compounds Emitted by Banana Plants (Musa sp.)
Berhal, Chadi ULg; De Clerck, Caroline ULg; LEVICEK, Carolina et al

Conference (2017, June 16)

Banana fruit (Musa sp.) ranks fourth in developing world's production, and has economical and nutritional key values. The popular and most dominant variety of the dessert banana group is the Cavendish ... [more ▼]

Banana fruit (Musa sp.) ranks fourth in developing world's production, and has economical and nutritional key values. The popular and most dominant variety of the dessert banana group is the Cavendish variety, and Plantain represents that status for the cooking banana group. Despite the importance of the Volatile Organic Compounds (VOCs), which are secondary metabolites with a high vapour pressure, in their utility in the plant protection and communication processes, they were never documented for the plant itself. Thus, the aim of this PHD thesis is to study the VOCs emitted by the plant, rather than their fruits or flowers. A protocol was optimized for the extraction of the banana plant's VOCs. The results of the first analysis showed 11 VOCs for the Cavendish, mainly (E,E)-α-farnesene (87.90 ± 11.28 ng/µl), methyl salicylate (33.82 ± 14.29) and 6-methyl-5-hepten-2-one (29.60 ± 11.66), and 14 VOCs for the Pacific Plantain cultivars, mainly (Z,E)-α-farnesene (799.64 ± 503.15),(E,E)-α-farnesene (571.24 ± 381.70) and (E) β ocimene (241.76 ± 158.49). Most of these compounds belong to the terpenes group (8 for Cavendish, 10 for Pacific Plantain). The other compounds detected were ketones, esters and aldehydes. Eight compounds were common between the two varieties (myrcene, Z and E β-ocimene, 6-methyl-5-hepten-2 one, 6-methyl-3,5-hepadien-2-one, a-farnesene, methyl salicylate and β-ionone). This exploratory study paves the way for an in-depth characterisation of VOCs emitted by Musa plants. [less ▲]

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See detailStudy of volatile organic compounds active against barley pathogens
De Clerck, Caroline ULg; Kaddes, Amine ULg; Fiers, Marie et al

Conference (2017, May 23)

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See detailStudy of VOCs in the interaction between Banana and Foc TR4
Berhal, Chadi ULg; De Clerck, Caroline ULg; LEVICEK, Carolina et al

Poster (2017, May 23)

Banana fruit (Musa sp.) ranks fourth in term of worldwide production, and has economical and nutritional key values. The popular and most dominant variety of the dessert banana group is the Cavendish ... [more ▼]

Banana fruit (Musa sp.) ranks fourth in term of worldwide production, and has economical and nutritional key values. The popular and most dominant variety of the dessert banana group is the Cavendish variety. Nowadays, the Cavendish is endangered by the newly emergent race of the Panama disease, caused by the fungal pathogen Fusarium oxysporum f.sp. cubense TR4 (Foc TR4). Despite the importance of the Volatile Organic Compounds (VOCs), which are secondary metabolites with a high vapour pressure, in their utility in the plant protection processes, they were never documented as a way to manage this disease on Cavendish. Thus, the aim of this PhD thesis is to study the VOCs in the specific interaction Cavendish/Foc TR4, as a way to manage this threat. Based on the work previously done with other plants at Gembloux Agro-Bio Tech/University of Liège/Belgium, a protocol was optimized for the extraction of the banana plant’s VOCs. And in parallel, models of in-vitro and in-vivo inoculations are under development, in order to distinguish the root zone from the upper part of the plant in the study. The results of the first analysis showed that the majority of the Cavendish VOCs belongs to the terpenes group, as well as ketones and an organic ester. The identified key VOCs of the interaction will be subject to toxicity tests, in order to determine their effect on the development of the plant and the pathogen. The banana plant is a staple food for more than 400 Million people in the world, while this disease persists as a major threat for its production, and this original study could contribute to the fight against this threatening disease. [less ▲]

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See detailFirst Characterisation of Volatile Organic Compounds Emitted by Banana Plants
Berhal, Chadi ULg; De Clerck, Caroline ULg; Fauconnier, Marie-Laure ULg et al

in Scientific Reports (2017)

Banana (Musa sp.) ranks fourth in term of worldwide fruit production, and has economical and nutritional key values. The Cavendish cultivars correspond to more than 90% of the production of dessert banana ... [more ▼]

Banana (Musa sp.) ranks fourth in term of worldwide fruit production, and has economical and nutritional key values. The Cavendish cultivars correspond to more than 90% of the production of dessert banana while cooking cultivars are widely consumed locally around the banana belt production area. Many plants, if not all, produce Volatile Organic Compounds (VOCs) as a means of communication with their environment. Although flower and fruit VOCs have been studied for banana, the VOCs produced by the plant have never been identified despite their importance in plant health and development. A volatile collection methodology was optimized to improve the sensitivity and reproducibility of VOCs analysis from banana plants. We have identified 11 VOCs for the Cavendish, mainly (E,E)-α-farnesene (87.90 ± 11.28 ng/μl), methyl salicylate (33.82 ± 14.29) and 6-methyl-5-hepten-2-one (29.60 ± 11.66), and 14 VOCs for the Pacific Plantain cultivar, mainly (Z,E)-α-farnesene (799.64 ± 503.15), (E,E)-α-farnesene (571.24 ± 381.70) and (E) β ocimene (241.76 ± 158.49). This exploratory study paves the way for an in-depth characterisation of VOCs emitted by Musa plants. [less ▲]

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See detailLessons learned from the virus indexing of Musa germplasm: insights from a multiyear collaboration
De Clerck, Caroline ULg; Crew, Kathy; Van den Houwe, Ines et al

in Annals of Applied Biology (2017)

The Bioversity International Transit Center (ITC) for banana hosts more than 1500 accessions largely covering the genetic diversity of the genus Musa. Its objective is to conserve this genetic diversity ... [more ▼]

The Bioversity International Transit Center (ITC) for banana hosts more than 1500 accessions largely covering the genetic diversity of the genus Musa. Its objective is to conserve this genetic diversity and to supply plant materials to users worldwide. All the Musa accessions must be tested for virus presence and, if infected, virus elimination must be attempted, to enable the supply of virus-free plant material. An international collaborative effort launched under the auspices of Bioversity International (2007–2013) finally led to the implementation of a two-step process to test the accessions. The first step, called pre-indexing, involved only molecular tests and was designed as a pre-screen of new germplasm lines or existing accessions to reduce the need for post-entry virus therapy and repeated virus indexing. The second step, called full indexing, was performed on either older existing accessions or newer accessions which tested negative during pre-indexing, and involvedmolecular tests, transmission electron microscopy (TEM) and symptom observation. In total, 270 germplasm lines (434 samples) were pre-indexed; while full indexing was carried out on 243 accessions (68 of which had been pre-indexed). A significant proportion of the samples tested during pre-indexing was infected with at least one virus (68%), showing the utility of this early pre-screening step. Banana streak OL virus and Banana mild mosaic virus were the most commonly detected viruses during both pre- and full indexing. For 22 accessions, viral particles were observed by TEM in full indexing while the molecular tests were negative, underlining the importance of combining various detection techniques. After full indexing, viruses were not detected in 166 accessions, which were then released for international distribution from the ITC. This publication exemplifies how the practical application of diagnostic protocols can raise fundamental questions related to their appropriate use in routine practice and the need for their continuous monitoring and improvement after their first publication. [less ▲]

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See detailStudy of the volatile organic compounds in the interaction between banana plants and the fungal disease Fusarium oxysporum f.sp. cubense Tropical Race 4 (FocTR4)
Berhal, Chadi ULg; De Clerck, Caroline ULg; LEVICEK, CAROLINA et al

Conference (2016, October 11)

Banana fruit (Musa sp.) ranks fourth in term of worldwide production, and has economical and nutritional key values. Cavendish is the popular and most dominant variety of the dessert banana group ... [more ▼]

Banana fruit (Musa sp.) ranks fourth in term of worldwide production, and has economical and nutritional key values. Cavendish is the popular and most dominant variety of the dessert banana group. Nowadays, it is endangered by the emergent race of the Panama disease, caused by Fusarium oxysporum f.sp. cubense TR4 (Foc TR4). Despite the importance of the Volatile Organic Compounds (VOCs), which are secondary metabolites with a high vapour pressure, and their role in plant protection, they have never been documented as a way to manage this disease on Cavendish. Thus, the aim of this PhD thesis is to study the VOCs in the specific interaction Cavendish/Foc TR4, as a way to manage this threat. Based on the work previously done with other plants at Gembloux Agro-Bio Tech, a protocol was optimized for the extraction of the banana plant’s VOCs. In parallel, models of in-vitro and in-vivo inoculations are under development to distinguish the VOCs emitted by the root zone and those emitted by the aerial part of the plant. The results of the first analysis showed that the majority of the Cavendish VOCs belongs to the terpenes group, as well as ketones and an organic ester. The VOCs specifically emitted during the plant-pathogen interaction will be studied more in depth by evaluating their effect on the plant and the pathogen. At long term, and depending on the results, agro-ecological applications of this knowledge could include breeding for new variety or combining banana with other plants expressing VOCs against Foc TR4, applying VOCs on field to stimulate plant defences or to contain the pathogen. [less ▲]

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See detailExtremophile plants as source of biopesticides against European damageable plant pathogens
Ben Kaab, Sofiène ULg; Parisi, Olivier ULg; De Clerck, Caroline ULg et al

Poster (2016, September 14)

The use of plant-derived products in postharvest disease management may be a valid alternative to conventional chemical treatments (Pane et al., 2016). Unfavorable environmental conditions (such as salt ... [more ▼]

The use of plant-derived products in postharvest disease management may be a valid alternative to conventional chemical treatments (Pane et al., 2016). Unfavorable environmental conditions (such as salt and drought) increase production and accumulation of reactive oxygen species (ROS). Consequently, extremophile plants have developed adaptive responses including the synthesis of specific bioactive molecules used for medical and nutritional purposes (Ksouri et al., 2012). In that context, the main objective of the present study was the identification of effective plant extracts and essential oils from extremophile plants against the most important plant pathogens in Europe (in term of loss, treatment necessity and/or cost). The study began with the selection of four endemic medicinal species suspected to be antimicrobial due to their wealth of phenolic and terpene compounds, such as flavonoids, phenolic acids, and coumarins (Ksouri et al., 2012). Each of the aerial plant materials was grounded and macerated with solvent (methanol or chloroform) for 24 h. The solvent was then eliminated along rotavapor. The yield of plant extract varied between 1.56 and 6.7%. Kinetics of growth of the 3 pathogens cultivable in liquid medium was determined before testing the impact of plant extracts and essential oils. Methanolic and chloroform plant extracts (EM1, EM2, EC1 and EC2) and essential oils (EO1, EO2) were compared for their antifungal potential. The chemical composition of the essential oils obtained by hydrodistillation from the aerial parts was analyzed by GC/MS. Yield of essential oil varied between 0.7 and 1.2%. Therefore, antifungal activity of plant extracts and essential oils was evaluated using ELISA microplates with a blocked randomized design, as described previously (Parisi et al., 2013). The results obtained showed that EM2 at 7 mg/ml has a very high fungistatic activity against Fusarium culmorum, F. oxysporum and Penicillium italicum. It was characterized with a high amount of polyphenols, flavonoids and condensed tannins. Statistical analysis showed that the efficiency of methanol extracts significantly differed from those of the chloroform extracts. In addition, essential oils significantly reduced spores germination in a dose-dependent manner. Their fungistatic activity reached 100% at 6000 ppm. In conclusion, this work allowed us to open new perspectives on the application of extremophile plant extracts as novel biocontrol strategy against plant pathogens. [less ▲]

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See detailVolatile Organic Compounds:a new tool to control barley pathogens?
Kaddes, Amine ULg; Massart, Sébastien ULg; Fauconnier, Marie-Laure ULg et al

Poster (2016, February 05)

Barley is threatened by various edaphic fungal diseases. In particular, common root rot caused by Fusarium culmorum and Cochliobolus sativus is causing between 9 and 23 % of yield losses. Today, since ... [more ▼]

Barley is threatened by various edaphic fungal diseases. In particular, common root rot caused by Fusarium culmorum and Cochliobolus sativus is causing between 9 and 23 % of yield losses. Today, since most of the chemicals used for crop protection are being forbidden, there is a growing need of sustainable ways to control these diseases. A recent study has shown that barley roots infected by common root rot emitted 23 Volatile Organic Compounds (VOCs) that were not emitted by healthy barley roots. In addition it was shown that the blend of these molecules negatively impacted the growth of the two fungi. The main objective of the present study was to determine which VOCs of the blend were the most efficient in this growth reduction, and to understand their mode of action. We have found that methyl propionate (MP) and methyl acrylate (MA) reduced significantly the development of the two fungi in vitro. We also observed an inhibition of the spores’ germination in the presence of the two esters. The effect of the two molecules on infected barley seeds was also tested. We have observed that the plants coming from the seeds in contact with the VOCs did not develop symptoms of the disease. The antifungal and antibacterial activity of these VOCs on a wider range of fungal and bacterial diseases was also tested in vitro with success The two esters that we have studied could thus be an interesting starting point in the development of a sustainable way to control barley’s diseases. [less ▲]

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See detailIdentification and characterization of volatile organic compounds active against barley pathogens
De Clerck, Caroline ULg; Kaddes, Amine ULg; Fiers, Marie et al

in Bulletin OILB/SROP = IOBC/WPRS Bulletin (2016), 117

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See detailA metagenomic approach from aphid’s hemolymph sheds light on the potential roles of co-existing endosymbionts
De Clerck, Caroline ULg; Fujiwara, Akiko; Joncour, Pauline et al

in Microbiome (2015), 3(63),

Background: Aphids are known to live in symbiosis with specific bacteria, called endosymbionts which can be classified as obligate or accessory. Buchnera aphidicola is generally the only obligatory ... [more ▼]

Background: Aphids are known to live in symbiosis with specific bacteria, called endosymbionts which can be classified as obligate or accessory. Buchnera aphidicola is generally the only obligatory symbiont present in aphids, supplying essential nutrients that are missing in the plants phloem to its host. Pentalonia nigronervosa is the main vector of the banana bunchy top virus, one of the most damageable viruses in banana. This aphid is carrying two symbionts: B. aphidicola (BPn) and Wolbachia sp. (wPn). The high occurrence of Wolbachia in the banana aphid raises questions about the role it plays in this insect. The goal of this study was to go further in the understanding of the role played by the two symbionts in P. nigronervosa. To do so, microinjection tests were made to see the effect of wPn elimination on the host, and then, high-throughput sequencing of the haemolymph was used to analyze the gene content of the symbionts. Results: We observed that the elimination of wPn systematically led to the death of aphids, suggesting that the bacterium could play a mutualistic role. In addition, we identify and annotate 587 and 250 genes for wPn and BPn, respectively, through high-throughput sequencing. Analysis of these genes suggests that the two bacteria are working together for the production of several essential nutrients. The most striking cases are for lysin and riboflavin which are usually provided by B. aphidicola alone to the host. In the banana aphid, the genes involved in the production pathways of these metabolites are shared between the two bacteria making them both essential for the survival of the aphid host. Conclusions: Our results suggest that a co-obligatory symbiosis between B. aphidicola and Wolbachia occurs in the banana aphid, the two bacteria acting together to supply essential nutrients to the host. This is, to our knowledge, the first time Wolbachia is reported to play an essential role in aphids. [less ▲]

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See detailIdentification of the bacterial symbionts of the banana aphid Pentalonia nigronervosa and characterization of their roles
De Clerck, Caroline ULg

Doctoral thesis (2015)

Les insectes sont caractérisés par une incroyable capacité d’adaptation à de nombreux environnements et modes d’alimentation, qui est liée au fait que la majorité des insectes (voire tous) hébergent des ... [more ▼]

Les insectes sont caractérisés par une incroyable capacité d’adaptation à de nombreux environnements et modes d’alimentation, qui est liée au fait que la majorité des insectes (voire tous) hébergent des symbiontes intra ou extracellulaires. Ces associations symbiotiques sont très diverses et peuvent aller d’un mutualisme obligatoire à un parasitisme facultatif. Les pucerons, en particulier, sont connus pour vivre en symbiose avec au moins une bactérie obligatoire qui leur fournit les nutriments essentiels absents du phloème dont ils se nourrissent : Buchnera aphidicola. La plupart des symbiontes d’insectes étant incultivables, les technologies moléculaires modernes se sont avérées des outils puissants dans la compréhension des interactions hôte-microorganisme et la caractérisation du rôle joués par ces symbiontes. Les études génomiques ont mené à la découverte des plus petits génomes bactériens jamais observés, et ont permis une étude plus poussée des symbiontes secondaires et de leur évolution. Pentalonia nigronervosa, le puceron noir du bananier, lest le vecteur principal du virus des sommets touffus du bananier, l’un des virus les plus dommageables en culture bananière. Très peu d’études sont néanmoins disponibles sur ce vecteur et rien n’était connu sur la population symbiotique hébergée par cet insecte jusqu’à cette étude. Dans cette thèse, nous avons découvert que le puceron du bananier contient deux symbiontes : B. aphidicola (BPn) et Wolbachia sp. (wPn); et cela dans tous les pucerons testés, quelle que soit leur origine géographique. La présence de Buchnera était attendue (99,9% de toutes les espèces de pucerons contiennent ce symbionte), mais la détection systématique de Wolbachia nous fait nous interroger sur le rôle que cette bactérie pourrait jouer pour l’insecte hôte, ainsi que sur la raison de sa présence. Wolbachia n’est en effet que rarement détectée chez les pucerons et est surtout connue pour être un parasite qui manipule le système reproducteur de ces hôtes. Malgré tout, des études ont montré que cette bactérie pouvait agir comme mutualiste pour certains insectes, ce qui pourrait expliquer sa présence dans le puceron du bananier. Le second objectif de cette étude a donc été de mieux comprendre le rôle joué par les deux symbiontes de P. nigronervosa. Pour ce faire, différentes techniques complémentaires ont été utilisées. La microinjection d’antibiotiques a été utilisée afin d’éliminer sélectivement wPn et de voir l’effet de cette élimination sur l’hôte. Nous avons observé que l’élimination de wPn donnait systématiquement lieu à la mort du puceron. Un séquençage haut débit de l’hémolymphe (contenant des bacteriocytes) d’un puceron a été réalisé et nous a permis d’identifier et d’annoter 587 et 250 gènes pour wPn et BPn respectivement. L’analyse de ces gènes nous permet d’émettre l’hypothèse que les deux bactéries collaborent pour la production de plusieurs nutriments essentiels pour l’hôte. La situation est surtout frappante dans le cas de la lysine et de la riboflavine, qui sont habituellement produits uniquement par Buchnera chez les autres espèces de pucerons. Dans le cas du puceron du bananier, les gènes impliqués dans les voies de production de ces métabolites sont répartis entre les génomes des deux bactéries, les rendant ainsi toutes les deux essentielles à la survie du puceron hôte. Enfin, une localisation par fluorescence in situ des deux symbiontes a montré qu’ils étaient tous deux localisés dans les bacteriocytes, rendant les échanges de précurseurs et métabolites possibles. En conclusion, nos résultats suggèrent que le puceron du bananier héberge une co-symbiose obligatoire entre B. aphidicola et Wolbachia, les deux bactéries agissant de concert dans l’approvisionnement de l’hôte en nutriments essentiels. [less ▲]

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See detailVolatile organic compounds emitted by Cavendish and Plantain banana plants
De Clerck, Caroline ULg; Kherkhofs, Celine; Berhal, Chadi ULg et al

Poster (2015, May 19)

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See detailStudy of essential oil activity on Curvularia sp. a rice leaf spot pathogen in Madagascar
Mamiharisoa Razanakoto, Léa ULg; Parisi, Olivier ULg; Massart, Sébastien ULg et al

Poster (2015, May 19)

Rice leaf spot have been observed on many fields during survey of rice diseases in three regions in Madagascar. Curvularia sp. was the most frequently isolated pathogen from the most severe diseased ... [more ▼]

Rice leaf spot have been observed on many fields during survey of rice diseases in three regions in Madagascar. Curvularia sp. was the most frequently isolated pathogen from the most severe diseased samples. This pathogen has been reported worldwide to cause important losses. Then in this work, we study the possibility to develop an alternative method to control Curvularia sp. Plants or plant extracts have been traditionally used to control human and plant diseases. Nowadays, the problem of residues of phytopharmaceutical products, reinforce the need for research on the development of natural plant extracts to control plant diseases. Madagascar has many endemic plants of interest. The antimicrobial properties of essential oils from Malagasy aromatic plants were evaluated. The main steps of this study are (i) the in-vitro screening of 39 Malagasy essential oils to control this pathogen, (ii) the evaluation of the phytotoxicity (on rice plants) of the efficient essential oils and (iii) the in vivo test of the activity of these non phytotoxic essential oils on Curvularia sp. on rice seedlings. The activity of essentials oils on Curvularia sp. has been tested in vitro during a microscale ELISA plate bioassay using optical density for a rapid evaluation of the biofungicidal activity of the extracts. Essential oils that showed interesting antifungal effect on this pathogen were tested for their phytotoxicity on rice plants. Briefly, one to two drop(s) of essential oils were applied on 3 leaves leaves of three weeks rice seedling. Six essential oils over the 39 tested showed an interesting antifungal activity with a percentage of growth inhibition greater than 70%. Three essential oils tested were phytotoxic as they induced necrotic spots on rice leaves after 48 h. Among three essential oils left, one of them showed an important effect when applied on rice seedling inoculated with a conidial suspension of Curvularia sp. These results confirmed that some essential oils present an antifungal activity. And even some of them are phytotoxic on rice plants, some essential oils show interesting potential to be an alternative method against rice diseases. [less ▲]

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See detailTechnical guidelines for the safe movement of Musa germplasm
Thomas, John; Sharman, Murray; Lassois, Ludivine ULg et al

in Thomas, John (Ed.) Technical guidelines for the safe movement of Musa germplasm (2015)

Detailed reference viewed: 30 (6 ULg)
See detailVirus indexing and sanitation of international banana collection: insights from a 5-years collaborative effort
De Clerck, Caroline ULg; Parmenter, Kathleen; Vandenhouwe, Ines et al

Conference (2015)

Detailed reference viewed: 37 (2 ULg)